Automotive steel tubes must meet tighter dimensional tolerances than standard industrial tubes. DIN 2391 Automotive Steel Tubes and EN 10305 precision tubes automotive are the two governing standards for seamless precision cold-drawn tubes used across the global automotive supply chain. The two standards give the same grade of material but have different names for the same grade. DIN 2391 and EN 10305-1 are technically equivalent: ST30 equals E155, ST35 equals E195, ST45 equals E235, and ST52 equals E355.
USA Piping Solution is a trusted automotive steel tubes manufacturer and exporter that are made according to DIN 2391 and EN 10305-1 standards. Seamless precision cold-drawn tubes in grades ST30 to ST52 are available with us for use in a variety of applications including hydraulic systems, suspension assemblies, transmission shafts, fuel delivery lines and steering components. Our tubes are shipped with full mill test reports, third party support and competitive lead time to automotive OEMs, tier-1 suppliers and distributors around the world. If you need a quote, send your request today, and we'll send it back to you in 24 hours or less. Our cold drawn seamless mechanical tubing range is EN-certified and export-ready. Whether you are qualifying a new supplier for a hydraulic cylinder program or need spot stock for a suspension strut project, we maintain ready inventory and can issue MTC documentation to DIN or EN designation on request.
DIN 2391 and EN 10305-1 Precision Tube Available Grades
Select a grade to access full chemical composition, mechanical property tables, and RFQ form. Our EN 10305-1 E235 carbon steel tubes page is live and detailed. Additional grade pages are being published progressively.
Request a Quote for DIN 2391 / EN 10305 Automotive Tubes
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DIN 2391 and EN 10305-1 Grade Equivalence
The table below is the definitive DIN-to-EN grade equivalence reference for automotive precision tubing. European OEM procurement teams and tube suppliers can use this as a single source of truth when aligning on grade designations across specifications, datasheets, and mill test certificates.
| DIN Grade | EN Grade | Min. Yield (MPa / ksi) | Min. Tensile (MPa / ksi) | Primary Application |
|---|---|---|---|---|
| ST30 | E155 | 155 MPa / 22.5 ksi | 270 MPa / 39.2 ksi | Low-pressure fuel and brake lines |
| ST35 | E195 | 195 MPa / 28.3 ksi | 320 MPa / 46.4 ksi | General hydraulic and fluid transfer |
| ST45 | E235 | 235 MPa / 34.1 ksi | 410 MPa / 59.5 ksi | Precision structural and motion control |
| ST52 | E355 | 355 MPa / 51.5 ksi | 490 MPa / 71.1 ksi | High-pressure hydraulic cylinders, suspension struts |
NOTE: Yield values in the EN column reflect the EN 10305-1 grade designation reference numbers, not DIN 2391 mechanical test minimums. DIN 2391 Part 2 specifies delivery-condition-dependent mechanical properties (BK, BKS, GBK, NBK) — contact our technical team for condition-specific test values or see individual grade pages
Size Range for DIN 2391 and EN 10305-1 Automotive Steel Tubes
We supply DIN 2391 and EN 10305-1 automotive steel tubes across the following dimensional range:
| Parameter | Range | Tolerance Class | Note |
|---|---|---|---|
| Outside Diameter (OD) | 4 mm to 120 mm | Precision Class: plus/minus 0.03 mm | Custom OD on request |
| Wall Thickness (WT) | 0.5 mm to 15 mm | DIN 2391 / EN 10305-1 Table | Heavy wall up to 20 mm on indent |
| Length | 4 m to 12 m (random or fixed) | Plus 0 / Minus 0 fixed length | Coil form for small OD |
| Surface Finish | Inner: honed or bright drawn | Ra 0.4 to 1.6 micron | SRB/honed on request |
For equivalent ASTM-standard precision tubing, refer to our ASTM A519 seamless mechanical tubing page. Buyers sourcing for North American OEM plants often cross-reference ASTM A519 Grade 1020 alongside DIN 2391 ST35 for equivalence assessment.
Need Automotive Steel Tubes?
Get competitive pricing, mill test certificates, and a fast 24-hour quotation turnaround. DIN 2391 and EN 10305-1 grades from stock: OD 4 mm to 120 mm.
Applications of Automotive Steel Tubes
Automotive steel tubes to DIN 2391 and EN 10305-1 are precision cold-drawn components engineered for tight-tolerance, safety-critical systems across the vehicle. Our Cold Drawn Seamless Mechanical Tubing range covers the full spectrum of automotive precision tube requirements.
Hydraulic Systems — ST52/E355 tubes are the standard choice for high-pressure hydraulic cylinders, brake actuators, and power steering lines where yield strength and bore consistency are critical.
Suspension & Structural Components — ST45/E235 and ST52/E355 grades are widely used in suspension struts, shock absorber cylinders, and structural cross-members requiring precise OD tolerances and consistent wall thickness.
Transmission & Driveline — ST45/E235 seamless precision tubes suit transmission shafts and motion control components where dimensional accuracy directly affects rotational performance.
Fuel & Brake Lines — ST30/E155 and ST35/E195 grades serve low-to-medium pressure fuel delivery and brake line applications where formability and leak-free integrity are the primary requirements.
Steering Components — Cold-drawn precision tubes in ST45/E235 are used in steering column assemblies and rack housings where tight OD tolerances and surface finish are essential for fit and function.
Frequently Asked Questions
Are DIN 2391 and EN 10305 the same standard?
Yes. DIN 2391 has been technically superseded by EN 10305-1. The grades are equivalent: ST30 equals E155, ST35 equals E195, ST45 equals E235, and ST52 equals E355. MTCs can be issued under either designation.
Which grade is recommended for hydraulic cylinder tubes?
ST52 (EN 10305-1 E355) is the preferred grade for hydraulic cylinders. It offers minimum yield of 355 MPa (51.5 ksi) and is available in NBK (bright annealed) delivery condition for honed bore applications.
Are honed (SRB) versions available?
Yes. We supply honed and skived-roller-burnished (SRB) tubes in ST52/E355 for hydraulic cylinder bores. Surface roughness Ra 0.4 micron achievable. Contact us with bore diameter and length requirements.
Share your grade, OD, WT, delivery condition, and destination. Our technical sales team will respond with pricing, lead time, and MTC format within 24 hours.
Email: sales@usapipingsolution.com
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